A 520-million-year-old fossil has provided evidence that complex brains evolved much earlier than previously thought

A 520-million-year-old fossil has provided evidence that complex brains evolved much earlier than previously thought. The 7.6-centimetre preserved skeleton belonged to Fuxianhuia protensa, an extinct invertebrate related to today’s spiders and insects, and contains remnants of optic nerves connected to a three-segment brain. This is the earliest known fossil to show a complex brain, according to the paper published in Nature.